Derusting ferrous metals



Patented June 4, I I I I UNITED STATES PATENT OFFICE.-

WILLIAM nowm COLE, or rams, rnmcn nnnusrme rnimous METALS.

No Drawing. Original application filed September 20, 1927, Serial No. 220,840; and in Great Britain August 22, 1927. Diyidcd and this application filed December 31, 1927. Serial No. 244,042:

This specification is a division of my specappearance very clean and free from rust. ification Serial No. 220,840, filed th Sep- I do not confine myself to the use of tcmber, 1927. dilute phosphoric acid for de-rusting as de- I have found that by treating rusted iron scribed above, as I find that my high pres- 5 or steel articles with dilute phosphoric acid, sure process gives excellent results with other in an autoclave, at high temperature and ingredients, for the compositions of which I'- pressure, the ruston the said article. is redo not claim. priority, but merely desire, in 40 moved. this respect, to be protected in the use of my The following example will further illushereinbefore described method of treatment 10 trate the nature of the invention. under pressure and high temperature, and

A steel container with a manhole opening the use of an autoclave-or closed vessel cawas made strong enough to withstand high pable ofavithstanding heat and pressure for pressure. This container was furnished rust-proofing and de-rusting ferrous metals. with a pressure gauge, a safety valve and in "Vhat I claim and desire to secure by Letv 15 addition a soft metal plug which would melt ters Patent is if the temperature rose too high, and so re 1. Process of de-rusting and removing lease the pressure, and finally a signal whisscale from; ferrous articles consisting in tle which whistled an alarm when the pres treating them with phosphoric acid so dilute sure inside rose to the predetermined point. that no'coating is left on thearticles treated 20 This whistle alarm was made to be ad ustaina closed vessel, said treatment being carblc for any pressure wanted. In, one exried out at boiling temperature and under periment, after introducing the ingredients pressure greater than atmospheric pressure. and steel and iron pieces to be de-rusted,- 2. Process of de-rusting and removing the pressure arranged for was about 50 scale from ferrous articles consistin in 25 pounds per square inch, the heating had; treating them with phos horic aci so only to be used for a period of about ten dilute that no coating is le on the articles minutes before the whistle gave the alarm treated in a closed vessel, said treatment beand thesource of heat wasturncd off. After ing carried out at a boiling temperature and the pressure vessel had cooled suificiently-to under a pressureof-about 50 pounds per 30 enable it to be opened without'danger, which square inch. i

in this case was about 10 minutes, the auto- In testimony whereof I aflix my signaclave was opened and it was ascertained ture. that the iron and steel pieces treated were in WILLIAM HOWARD COLE. 

